Anything with fur can get fleas and ticks. I have no idea the preventative measure though. I don’t think it’s safe to put a flea collar on a bunny. And I have never had a pet that had fleas so I am clueless.

No, I haven’t yet.  I’ve only had her 5 months and it’s still quite wintery here.  

Yes bunnies can get fleas, but I’d think that fleas are the least among other worries when it comes to bringing bunnies outside since they can be treated quite easily even if bunny does get them. As Kiki mentioned, flea collars are also not safe for bunnies.

Currently in the US, certain parts of Europe and Australia there’s a fatal virus called RHD2 that has affected many bunnies. Personally I’m not in any of these areas but if you are, it’s best to keep your bunny indoors to minimise the risk of them contracting the virus. Although indoor buns can get it too, the risk seems to be higher outdoors as the virus can pass through birds, foxes etc. and their droppings could bring an infection. Vaccinations are available – I suggest reading up on this virus and its prevention if you’re in an affected area.

There’s also the risk of predators like hawks or cats that could potentially harm your bunny – some people prevent this by putting a covered playpen outside and making sure the bunny is supervised during playtime. Overall there are many people who prefer not taking their bunny outside, but if you really want to, make sure you have researched on all the potential risks and make the necessary precautions